<!--
  ****************************************************************************
  * Copyright 2018-2024,2025 Thomas E. Dickey                                *
  * Copyright 2008-2016,2017 Free Software Foundation, Inc.                  *
  *                                                                          *
  * Permission is hereby granted, free of charge, to any person obtaining a  *
  * copy of this software and associated documentation files (the            *
  * "Software"), to deal in the Software without restriction, including      *
  * without limitation the rights to use, copy, modify, merge, publish,      *
  * distribute, distribute with modifications, sublicense, and/or sell       *
  * copies of the Software, and to permit persons to whom the Software is    *
  * furnished to do so, subject to the following conditions:                 *
  *                                                                          *
  * The above copyright notice and this permission notice shall be included  *
  * in all copies or substantial portions of the Software.                   *
  *                                                                          *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS  *
  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF               *
  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.   *
  * IN NO EVENT SHALL THE ABOVE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,   *
  * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR    *
  * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR    *
  * THE USE OR OTHER DEALINGS IN THE SOFTWARE.                               *
  *                                                                          *
  * Except as contained in this notice, the name(s) of the above copyright   *
  * holders shall not be used in advertising or otherwise to promote the     *
  * sale, use or other dealings in this Software without prior written       *
  * authorization.                                                           *
  ****************************************************************************
  * @Id: tabs.1,v 1.70 2025/02/15 14:55:00 tom Exp @
-->
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN">
<HTML>
<HEAD>
<meta http-equiv="Content-Type" content="text/html; charset=us-ascii">
<meta name="generator" content="Manpage converted by man2html - see https://invisible-island.net/scripts/readme.html#others_scripts">
<TITLE>tabs 1 2025-02-15 ncurses 6.5 User commands</TITLE>
<link rel="author" href="mailto:bug-ncurses@gnu.org">

</HEAD>
<BODY>
<H1 class="no-header">tabs 1 2025-02-15 ncurses 6.5 User commands</H1>
<PRE>
<STRONG><A HREF="tabs.1.html">tabs(1)</A></STRONG>                          User commands                         <STRONG><A HREF="tabs.1.html">tabs(1)</A></STRONG>




</PRE><H2><a name="h2-NAME">NAME</a></H2><PRE>
       <STRONG>tabs</STRONG> - set terminal tab stops


</PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
       <STRONG>tabs</STRONG> [<EM>options</EM>] [<EM>tabstop-list</EM>]


</PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
       The  <STRONG>tabs</STRONG> program clears and sets tab-stops on the terminal.  This uses
       the terminfo <STRONG>clear_all_tabs</STRONG> and <STRONG>set_tab</STRONG>  capabilities.   If  either  is
       absent,  <STRONG>tabs</STRONG> is unable to clear/set tab-stops.  The terminal should be
       configured to use hard tabs, e.g.,

           stty tab0

       Like <STRONG><A HREF="clear.1.html">clear(1)</A></STRONG>, <STRONG>tabs</STRONG> writes to the standard output.   You  can  redirect
       the  standard  output  to  a  file  (which  prevents <STRONG>tabs</STRONG> from actually
       changing the tabstops), and later <STRONG>cat</STRONG> the file to the  screen,  setting
       tabstops at that point.

       These   are   hardware   tabs,  which  cannot  be  queried  rapidly  by
       applications running in the terminal, if  at  all.   Curses  and  other
       full-screen  applications  may  use  hardware  tabs in optimizing their
       output to the terminal.  If  the  hardware  tabstops  differ  from  the
       information  in  the  terminal  database,  the result is unpredictable.
       Before running curses programs, you should either  reset  tab-stops  to
       the standard interval

           tabs -8

       or  use the <STRONG>reset</STRONG> program, since the normal initialization sequences do
       not ensure that tab-stops are reset.


</PRE><H2><a name="h2-OPTIONS">OPTIONS</a></H2><PRE>

</PRE><H3><a name="h3-General-Options">General Options</a></H3><PRE>
       <STRONG>-T</STRONG><EM>name</EM>
            Tell <STRONG>tabs</STRONG> which terminal type to  use.   If  this  option  is  not
            given,  <STRONG>tabs</STRONG>  will use the <STRONG>$TERM</STRONG> environment variable.  If that is
            not set, it will use the <EM>ansi+tabs</EM> entry.

       <STRONG>-d</STRONG>   The debugging option shows a ruler  line,  followed  by  two  data
            lines.   The  first  data line shows the expected tab-stops marked
            with asterisks.  The second data line shows the actual  tab-stops,
            marked with asterisks.

       <STRONG>-n</STRONG>   This  option tells <STRONG>tabs</STRONG> to check the options and run any debugging
            option, but not to modify the terminal settings.

       <STRONG>-V</STRONG>   reports the version of <EM>ncurses</EM> which was used in this program, and
            exits.

       The <STRONG>tabs</STRONG> program processes a single list of tab stops.  The last option
       to be processed which defines a list is the  one  that  determines  the
       list to be processed.


</PRE><H3><a name="h3-Implicit-Lists">Implicit Lists</a></H3><PRE>
       Use  a  single number as an option, e.g., "<STRONG>-5</STRONG>" to set tabs at the given
       interval (in this case 1, 6, 11, 16, 21, etc.).  Tabs are  repeated  up
       to the right margin of the screen.

       Use "<STRONG>-0</STRONG>" to clear all tabs.

       Use "<STRONG>-8</STRONG>" to set tabs to the standard interval.


</PRE><H3><a name="h3-Explicit-Lists">Explicit Lists</a></H3><PRE>
       An  explicit list can be defined after the options (this does not use a
       "-").  The values in the list must be in increasing numeric order,  and
       greater  than  zero.   They  are  separated  by a comma or a blank, for
       example,

           tabs 1,6,11,16,21
           tabs 1 6 11 16 21

       Use a "+" to treat a number as an increment relative  to  the  previous
       value, e.g.,

           tabs 1,+5,+5,+5,+5

       which is equivalent to the 1,6,11,16,21 example.


</PRE><H3><a name="h3-Predefined-Tab-Stops">Predefined Tab Stops</a></H3><PRE>
       POSIX defines several predefined lists of tab stops.

       <STRONG>-a</STRONG>   Assembler, IBM S/370, first format
            1,10,16,36,72

       <STRONG>-a2</STRONG>  Assembler, IBM S/370, second format
            1,10,16,40,72

       <STRONG>-c</STRONG>   COBOL, normal format
            1,8,12,16,20,55

       <STRONG>-c2</STRONG>  COBOL compact format
            1,6,10,14,49

       <STRONG>-c3</STRONG>  COBOL compact format extended
            1,6,10,14,18,22,26,30,34,38,42,46,50,54,58,62,67

       <STRONG>-f</STRONG>   FORTRAN
            1,7,11,15,19,23

       <STRONG>-p</STRONG>   PL/I
            1,5,9,13,17,21,25,29,33,37,41,45,49,53,57,61

       <STRONG>-s</STRONG>   SNOBOL
            1,10,55

       <STRONG>-u</STRONG>   UNIVAC 1100 Assembler
            1,12,20,44


</PRE><H3><a name="h3-Margins">Margins</a></H3><PRE>
       A  few  terminals  expose  a  means  of  changing  their left and right
       margins.  <STRONG>tabs</STRONG> supports this feature with an option.

       <STRONG>+m</STRONG> <EM>margin</EM>
            The  effect  depends  on  whether  the  terminal  has  the  margin
            capabilities:

            <STRONG>o</STRONG>   If  the  terminal provides the capability for setting the left
                margin, <STRONG>tabs</STRONG> uses this, and adjusts  the  available  tab  stop
                widths.

            <STRONG>o</STRONG>   If the terminal does not provide the margin capabilities, <STRONG>tabs</STRONG>
                imitates their effect, putting tab stops at appropriate places
                on each line.  The terminal's left margin is not modified.

            If the <EM>margin</EM> parameter is omitted, the default is 10.  Use <STRONG>+m0</STRONG> to
            reset the left margin, that is, to make it the left  edge  of  the
            terminal's display.  Before setting a left margin, <STRONG>tabs</STRONG> resets the
            margin to reduce problems that might arise from moving the  cursor
            to the left of the current left margin.

       When  setting  or  resetting  the  left margin, <STRONG>tabs</STRONG> may also reset the
       right margin.


</PRE><H2><a name="h2-FILES">FILES</a></H2><PRE>
       <EM>/usr/share/tabset</EM>
              tab stop initialization database


</PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
       IEEE  Std   1003.1/The   Open   Group   Base   Specifications   Issue 7
       (POSIX.1-2008) describes a <EM>tabs</EM> utility.  However,

       <STRONG>o</STRONG>   this  standard  describes  a  <STRONG>+m</STRONG>  option  to  set a terminal's left
           margin.  Very few of the entries in the terminal  database  provide
           the   <STRONG>set_left_margin</STRONG>   (<STRONG>smgl</STRONG>)   or   <STRONG>set_left_margin_parm</STRONG>  (<STRONG>smglp</STRONG>)
           capabilities needed to support the feature.

       <STRONG>o</STRONG>   Unlike <EM>tput</EM>, <EM>tabs</EM> has no specification in X/Open Curses Issue 7.

       The <STRONG>-d</STRONG> (debug) and  <STRONG>-n</STRONG>  (no-op)  options  are  <EM>ncurses</EM>  extensions  not
       provided by other implementations.


</PRE><H2><a name="h2-HISTORY">HISTORY</a></H2><PRE>
       A  <EM>tabs</EM>  utility  appeared  in  PWB/Unix 1.0 (1977).  A reduced version
       shipped in Seventh Edition Unix (early 1979) and  in  3BSD  (later  the
       same  year);  it  supported an option "-n" to set the first tab stop at
       the left margin.  That option is not specified by POSIX.

       The PWB/Unix <EM>tabs</EM> utility returned  in  System  III  (1980),  and  used
       built-in  tables  to  support  a half-dozen hardcopy terminal (printer)
       types.  It also had logic to support setting the left margin,  as  well
       as a feature for copying the tab settings from a file.

       Versions  of  the program in later releases of AT&amp;T Unix, such as SVr4,
       added support for the terminal database, but  retained  the  tables  to
       support the printers.  By this time, System V <EM>tput</EM> had incorporated the
       tab stop initialization feature of BSD's <EM>tset</EM> from 1982,  but  employed
       the <EM>terminfo</EM> database to do so.

       The  <STRONG>+m</STRONG>  option was documented in the POSIX Base Specifications Issue 5
       (Unix98, 1997), then omitted in Issue 6 (Unix03, 2004) without  express
       motivation,  though an introductory comment "and optionally adjusts the
       margin"  remains,  overlooked  in  the  removal.   The   <EM>tabs</EM>   utility
       documented  in Issues 6 and later has no mechanism for setting margins.
       The <STRONG>+m</STRONG> option in <EM>ncurses</EM>'s implementation differs from the SVr4 feature
       by using terminal capabilities rather than built-in tables.

       POSIX   documents   no  limit  on  the  number  of  tab  stops.   Other
       implementations impose one; the limit is 20 in PWB/Unix's <EM>tabs</EM> utility.
       While  some  terminals may not accept an arbitrary number of tab stops,
       <EM>ncurses</EM> attempts to set tab stops up to the right margin  if  the  list
       thereof is sufficiently long.

       The  "Rationale" section of the Issue 6 <EM>tabs</EM> reference page details how
       the committee considered  redesigning  the  <EM>tabs</EM>  and  <EM>tput</EM>  utilities,
       without settling on an improved solution.  It claims that

           no  known  historical  version  of  <EM>tabs</EM> supports the capability of
           setting arbitrary tab stops.

       The  feature  described  in  subsection  "Explicit  Lists"  above   was
       implemented  in  PWB/Unix,  and  permitted the setting of arbitrary tab
       stops nevertheless.


</PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
       <STRONG><A HREF="infocmp.1m.html">infocmp(1m)</A></STRONG>, <STRONG><A HREF="tset.1.html">tset(1)</A></STRONG>, <STRONG><A HREF="ncurses.3x.html">curses(3x)</A></STRONG>, <STRONG><A HREF="terminfo.5.html">terminfo(5)</A></STRONG>



ncurses 6.5                       2025-02-15                           <STRONG><A HREF="tabs.1.html">tabs(1)</A></STRONG>
</PRE>
<div class="nav">
<ul>
<li><a href="#h2-NAME">NAME</a></li>
<li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
<li><a href="#h2-DESCRIPTION">DESCRIPTION</a></li>
<li><a href="#h2-OPTIONS">OPTIONS</a>
<ul>
<li><a href="#h3-General-Options">General Options</a></li>
<li><a href="#h3-Implicit-Lists">Implicit Lists</a></li>
<li><a href="#h3-Explicit-Lists">Explicit Lists</a></li>
<li><a href="#h3-Predefined-Tab-Stops">Predefined Tab Stops</a></li>
<li><a href="#h3-Margins">Margins</a></li>
</ul>
</li>
<li><a href="#h2-FILES">FILES</a></li>
<li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
<li><a href="#h2-HISTORY">HISTORY</a></li>
<li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>
</ul>
</div>
</BODY>
</HTML>
